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Theses

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1994 - 19953
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Author: Kau × End date: 1995 × Start date: 1990 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Influence of storage on the quality of selected pulses
    (Department of Home Science, College of Agriculture, Vellayani, 1995) Bhanu Lekha, T; KAU; Prema, L
    Blackgram, greengram, horsegram and cowpea were the pulses commonly cultivated in Kerala. Area under cultivation was in the range of 21 cents to 1 acre and 10 to 90 kg of pulses were harvested every time. Pre harvest loss of crops were mainly due to insect attack. Conventional methods of pretreatments such as sundrying and sand mixing were administered. Prior to storage, for seed material, fungicide and insecticide were also used. Quantitative, qualitative and organoleptic changes such as weight loss, colour change texture change, inferior taste and discolouration due to storage were reported by the farmers. Forty five godowns were selected for the large scale storage study. Space facilities of the godown decided the number of pulses stored and duration of storage. Every month pulses were procured from Tamilnadu, Karnataka, Uttar Pradesh, Maharashtra and Madhya Pradesh. Prior to storage, pretreatments such as sparying DDVP, sweeping and dusting DT were administered. Infected pulses were sold as cattle feed and as manure or sold at subsidredrate for human consumption. Decrease in protein content, and volume expansion in all the pulses stored under large scale as well as farm level storage were noticed. While increase in no-protein-nitrogen, uric acid, moisture, cooking time, water uptake, percent hydration coefficient, damaged fraction, percent weight loss fungal contamination and bacterial contamination were observed in all the pulses irrespective of storage containers, storage period and level of storage.
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    ThesisItemOpen Access
    Vertical movement of nitrogen in major rice soils of Kerala
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1995) George Abraham, T; Kau; Pushkala, S
    An experiment was conducted at the College of Agriculture, Vellayani, to assess the leaching and runoff losses of applied fertilizer nitrogen in typical, major rice growing soils of kerala, with varying physical and chemical properties. Undisturbed vertical columns were used for the leaching study. The runoff study was conducted as a pot experiment using surface soil samples. The study revealed that the Onattukara soil recorded the highest leaching loss of applied nitrogen (56.10%). Kayal soil showed the lowest leaching percentage of 24.21. The quantity of leachate collected per unit time was also found to be the maximum in the case of Onattukara soil (185.51 ml/hr) and least in the case of Kayal soil (155.60 ml/hr). Correlation studies revealed that the leaching loss of nitrogen was negatively correlated with organic matter (-0.5593), cation exchange capacity (-0.4560), clay (-0.5864), bulk density (-0.3213) and water holding capacity (-0.5544). The leaching loss was positively correlated with the quantity of leachate collected per unit time (+0.8876). In the case of Onattukara and kole soils, the loss of nitrogen through leaching was observed till the fifth day. For Kari soils, the loss stopped completely by the 10th day. The Karappadam and Pattambi soils showed leaching till the 15th day. However, in the case of Kayal soils, the leaching loss continued through the whole period of the study. In all cases, maximum amount of leaching occurred during the first five days after fertilizer application and after that the loss was in negligible quantities. In the case of runoff study also, Onattukara soil showed the highest runoff loss of applied nitrogen (40.41). The least loss was shown by karappadam soil (15.70%). The runoff loss was found to decrease with increase in number of days. Even though, Karappadam soils showed the lowest runoff loss of applied nitrogen, it had the highest percentage difference in runoff loss (77.8%) and the least was shown by Onattukara and Pattambi soils (63.5%). Correlation studies revealed that the runoff loss of fertilizer nitrogen was found to be negatively correlated with the oprganic matter (-0.1248), cation exchange capacity (-0.0324), clay (-0.4135), water holding capacity 9-0.6723) and bulk density (-o.4659).
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    ThesisItemOpen Access
    Investigations on mosaic disease of bitter gourd
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1994) Purushothaman, S M; Kau; Rajagopalan, B
    Bitter gourd mosaic virus disease commonly occurring in Kerala was investigated. The symptoms appeared as typical mosaic mottling with dark green and light green patches. Diseased plants were severely stunted and produced only a few flowers and fruits. Transmission studies showed that the virus could be transmitted through mechanical means, grafting and by aphid vectors. The virus was found to be transmitted by the aphids aphis gossypii Glov., Aphis malvae Koch., Myzus persicae Sclz. And aphis craccivora Koch. Among the four species of aphids, A. gossypii and A. malvae were found to be the most efficient vectors. Investigations on the physical properties of the virus revealed that the virus had a thermal inactivation point between 50 and 600C, dilution end point between 1:1000 and 1:10000, longevity in vitro between 12 and 24 h at room temperature (28 - 300C) and 48 and 72 h at 100c. The minimum acquisition feeding and inoculation feeding period of the vector A. malvae were found to be 30s and I min respectively. But the percentage of transmission was maximum when an acquisition feeding period of 30 min and inoculation feeding period of 2 h were given. Influence of starvation before acquisition and inoculation feeding period proved that pre – acquisition starvation for 2 h produced maximum infection but post- acquisition starvation decreased the per cent infection. The vector could retain the virus for I h only. A single aphid could transmit the virus to healthy test plants, but maximum percentage of transmission was obtained with 10 aphids. Host range studies showed that the virus was restricted to the members of the family Araceae, Chenopodiaceae, Cucurbitaceae, Musaceae, Polygonaceae and Solanaceae. Datura metal acted as a symptomless carrier of bitter gourd mosaic virus. Serological studies showed that bitter gourd mosaic virus is related to cucumber mosaic virus, pumpkin mosaic virus and snake gourd mosaic virus. Varietal screening showed that all the varieties and collections were susceptible to biter gourd mosaic virus infection, but the variety Arka Harit and the collections 87 green long 1 C 68234, 61 white medium 1C 45358 and 177 green medium 1C 68324 were least susceptible. Studies on estimation of loss revealed that early infection of bitter gourd plants by the virus significantly reduced the number of leaves, leaf area, intermodal length, thickness of vines, length of vines, number of branches, number of flowers, number of fruits and other fruit characters viz., length of fruits, girth of fruits, weight of fruits and total yield of fruits.